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- Helbig, K. L., et al.
(författare)
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De Novo Pathogenic Variants in CACNA1E Cause Developmental and Epileptic Encephalopathy with Contractures, Macrocephaly, and Dyskinesias
- 2018
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Ingår i: American Journal of Human Genetics. - : Elsevier BV. - 0002-9297 .- 1537-6605. ; 103:5, s. 666-678
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Tidskriftsartikel (refereegranskat)abstract
- Developmental and epileptic encephalopathies (DEEs) are severe neurodevelopmental disorders often beginning in infancy or early childhood that are characterized by intractable seizures, abundant epileptiform activity on EEG, and developmental impairment or regression. CACNA1E is highly expressed in the central nervous system and encodes the alpha(1)-subunit of the voltage-gated Ca(V)2.3 channel, which conducts high voltage-activated R-type calcium currents that initiate synaptic transmission. Using next-generation sequencing techniques, we identified de novo CACNA1E variants in 30 individuals with DEE, characterized by refractory infantile-onset seizures, severe hypotonia, and profound developmental impairment, often with congenital contractures, macrocephaly, hyperkinetic movement disorders, and early death. Most of the 14, partially recurring, variants cluster within the cytoplasmic ends of all four S6 segments, which form the presumed Ca(V)2.3 channel activation gate. Functional analysis of several S6 variants revealed consistent gain-of-function effects comprising facilitated voltage-dependent activation and slowed inactivation. Another variant located in the domain II S4-S5 linker results in facilitated activation and increased current density. Five participants achieved seizure freedom on the anti-epileptic drug topiramate, which blocks R-type calcium channels. We establish pathogenic variants in CACNA1E as a cause of DEEs and suggest facilitated R-type calcium currents as a disease mechanism for human epilepsy and developmental disorders.
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- Wang, T, et al.
(författare)
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Large-scale targeted sequencing identifies risk genes for neurodevelopmental disorders
- 2020
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Ingår i: Nature communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 11:1, s. 4932-
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Tidskriftsartikel (refereegranskat)abstract
- Most genes associated with neurodevelopmental disorders (NDDs) were identified with an excess of de novo mutations (DNMs) but the significance in case–control mutation burden analysis is unestablished. Here, we sequence 63 genes in 16,294 NDD cases and an additional 62 genes in 6,211 NDD cases. By combining these with published data, we assess a total of 125 genes in over 16,000 NDD cases and compare the mutation burden to nonpsychiatric controls from ExAC. We identify 48 genes (25 newly reported) showing significant burden of ultra-rare (MAF < 0.01%) gene-disruptive mutations (FDR 5%), six of which reach family-wise error rate (FWER) significance (p < 1.25E−06). Among these 125 targeted genes, we also reevaluate DNM excess in 17,426 NDD trios with 6,499 new autism trios. We identify 90 genes enriched for DNMs (FDR 5%; e.g., GABRG2 and UIMC1); of which, 61 reach FWER significance (p < 3.64E−07; e.g., CASZ1). In addition to doubling the number of patients for many NDD risk genes, we present phenotype–genotype correlations for seven risk genes (CTCF, HNRNPU, KCNQ3, ZBTB18, TCF12, SPEN, and LEO1) based on this large-scale targeted sequencing effort.
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- Hammarsjö, A., et al.
(författare)
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High diagnostic yield in skeletal ciliopathies using massively parallel genome sequencing, structural variant screening and RNA analyses
- 2021
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Ingår i: Journal of Human Genetics. - : Springer Nature. - 1434-5161 .- 1435-232X. ; 66:10, s. 995-1008
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Tidskriftsartikel (refereegranskat)abstract
- Skeletal ciliopathies are a heterogenous group of disorders with overlapping clinical and radiographic features including bone dysplasia and internal abnormalities. To date, pathogenic variants in at least 30 genes, coding for different structural cilia proteins, are reported to cause skeletal ciliopathies. Here, we summarize genetic and phenotypic features of 34 affected individuals from 29 families with skeletal ciliopathies. Molecular diagnostic testing was performed using massively parallel sequencing (MPS) in combination with copy number variant (CNV) analyses and in silico filtering for variants in known skeletal ciliopathy genes. We identified biallelic disease-causing variants in seven genes: DYNC2H1, KIAA0753, WDR19, C2CD3, TTC21B, EVC, and EVC2. Four variants located in non-canonical splice sites of DYNC2H1, EVC, and KIAA0753 led to aberrant splicing that was shown by sequencing of cDNA. Furthermore, CNV analyses showed an intragenic deletion of DYNC2H1 in one individual and a 6.7 Mb de novo deletion on chromosome 1q24q25 in another. In five unsolved cases, MPS was performed in family setting. In one proband we identified a de novo variant in PRKACA and in another we found a homozygous intragenic deletion of IFT74, removing the first coding exon and leading to expression of a shorter message predicted to result in loss of 40 amino acids at the N-terminus. These findings establish IFT74 as a new skeletal ciliopathy gene. In conclusion, combined single nucleotide variant, CNV and cDNA analyses lead to a high yield of genetic diagnoses (90%) in a cohort of patients with skeletal ciliopathies.
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- Nilsson, D., et al.
(författare)
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Whole-Genome Sequencing of Cytogenetically Balanced Chromosome Translocations Identifies Potentially Pathological Gene Disruptions and Highlights the Importance of Microhomology in the Mechanism of Formation
- 2017
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Ingår i: Human Mutation. - : John Wiley & Sons. - 1059-7794 .- 1098-1004. ; 38:2, s. 180-192
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Tidskriftsartikel (refereegranskat)abstract
- Most balanced translocations are thought to result mechanistically from nonhomologous end joining or, in rare cases of recurrent events, by nonallelic homologous recombination. Here, we use low-coverage mate pair whole-genome sequencing to fine map rearrangement breakpoint junctions in both phenotypically normal and affected translocation carriers. In total, 46 junctions from 22 carriers of balanced translocations were characterized. Genes were disrupted in 48% of the breakpoints; recessive genes in four normal carriers and known dominant intellectual disability genes in three affected carriers. Finally, seven candidate disease genes were disrupted in five carriers with neurocognitive disabilities (SVOPL, SUSD1, TOX, NCALD, SLC4A10) and one XX-male carrier with Tourette syndrome (LYPD6, GPC5). Breakpoint junction analyses revealed microhomology and small templated insertions in a substantive fraction of the analyzed translocations (17.4%; n = 4); an observation that was substantiated by reanalysis of 37 previously published translocation junctions. Microhomology associated with templated insertions is a characteristic seen in the breakpoint junctions of rearrangements mediated by error-prone replication-based repair mechanisms. Our data implicate that a mechanism involving template switching might contribute to the formation of at least 15% of the interchromosomal translocation events.
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- Schoumans, J, et al.
(författare)
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Detection and delineation of an unusual 17p11.2 deletion by array-CGH and refinement of the Smith-Magenis syndrome minimum deletion to similar to 650 kb
- 2005
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Ingår i: European Journal of Medical Genetics. - : Elsevier BV. - 1769-7212. ; 48:3, s. 290-300
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Tidskriftsartikel (refereegranskat)abstract
- Smith-Magenis syndrome (SMS) is a multiple congenital anomaly/mental retardation syndrome and it is characterized by an interstitial deletion of chromosome 17p11.2. SMS patients have a distinct phenotype which is believed to be caused by haploinsufficiency of one or more genes in the associated deleted region. Five non-deletion patients with classical phenotypic features of SMS have been reported with mutations in the retinoic acid induced I (RAII) gene, located within the SMS critical interval. Happloinsufficiency of the RAII gene is likely to be the responsible gene for the majority of the SMS features, but other deleted genes in the SMS region may modify the overall phenotype in the patients with 17p11.2 deletions. SMS is usually diagnosed in the clinical genetic setting by FISH analysis using commercially available probes. We detected a submicroscopic deletion in 17p11.2 using array-CGH with a resolution of approximately 1 Mb in a patient with the SMS phenotype, who was not deleted for the commercially available SMS microdeletion FISH probe. Delineation of the deletion was performed using a 32K tiling BAC-array, containing 32,500 BAC clones. The deletion in this patient was size mapped to 2.7 Mb and covered the RAII gene. This case enabled the refinement of the SMS minimum deletion to similar to 650 kb containing eight putative genes and one predicted gene. In addition, it demonstrates the importance to investigate deletion of RAII in SMS patients.
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| 20. |
- Shahsavani, M, et al.
(författare)
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An in vitro model of lissencephaly : expanding the role of DCX during neurogenesis
- 2018
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Ingår i: Molecular Psychiatry. - : Nature Publishing Group. - 1359-4184 .- 1476-5578. ; 23:7, s. 1674-1684
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Tidskriftsartikel (refereegranskat)abstract
- Lissencephaly comprises a spectrum of brain malformations due to impaired neuronal migration in the developing cerebral cortex. Classical lissencephaly is characterized by smooth cerebral surface and cortical thickening that result in seizures, severe neurological impairment and developmental delay. Mutations in the X-chromosomal gene DCX, encoding doublecortin, is the main cause of classical lissencephaly. Much of our knowledge about DCX-associated lissencephaly comes from post-mortem analyses of patient's brains, mainly since animal models with DCX mutations do not mimic the disease. In the absence of relevant animal models and patient brain specimens, we took advantage of induced pluripotent stem cell (iPSC) technology to model the disease. We established human iPSCs from two males with mutated DCX and classical lissencephaly including smooth brain and abnormal cortical morphology. The disease was recapitulated by differentiation of iPSC into neural cells followed by expression profiling and dissection of DCX-associated functions. Here we show that neural stem cells, with absent or reduced DCX protein expression, exhibit impaired migration, delayed differentiation and deficient neurite formation. Hence, the patient-derived iPSCs and neural stem cells provide a system to further unravel the functions of DCX in normal development and disease.Molecular Psychiatry advance online publication, 19 September 2017; doi:10.1038/mp.2017.175.
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- Smeds, H., et al.
(författare)
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X-linked Malformation and Cochlear Implantation
- 2017
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Ingår i: Otology and Neurotology. - : Ovid Technologies (Wolters Kluwer Health). - 1531-7129 .- 1537-4505. ; 38:1, s. 38-46
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Tidskriftsartikel (refereegranskat)abstract
- Objective: To evaluate if cochlear implantation is safe and constitutes an option for hearing rehabilitation of children with x-linked inner ear malformation. Study Design: Retrospective patient review in combination with a multidisciplinary follow-up. Patients: Ten children with severe-profound mixed hearing loss and radiological findings consistent with Incomplete Partition type 3 cochlear malformation received cochlear implants during the years 2007 to 2015. Nine of the children had a mutation affecting the gene POU3F4 on Xq21. Main Outcome Measures: Surgical events, intraoperative measures and electrical stimulation levels, hearing and spoken language abilities. Results: In all, 15 cochlear implantations were performed. In three cases the electrode was found to be in the internal auditory canal on intraoperative x-ray and repositioned successfully. One child had a postoperative rhinorrhea confirmed to be cerebrospinal fluid but this resolved on conservative treatment. No severe complications occurred. Postoperative electrical stimulation levels were higher in 9 of 10 children, as compared with typically reported average levels in patients with a normal cochlea. Eight patients developed spoken language to various degrees while two were still at precommunication level. However, speech recognition scores were lower than average pediatric cases. Conclusion: Cochlear implantation is a safe procedure for children with severe-profound mixed hearing loss related to POU3F4 mutation inner ear malformation. The children develop hearing and spoken language but outcome is below average for pediatric CI recipients.
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| 24. |
- Verberne, EA, et al.
(författare)
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DNA Methylation Signature for JARID2-Neurodevelopmental Syndrome
- 2022
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Ingår i: International journal of molecular sciences. - : MDPI AG. - 1422-0067. ; 23:14
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Tidskriftsartikel (refereegranskat)abstract
- JARID2 (Jumonji, AT Rich Interactive Domain 2) pathogenic variants cause a neurodevelopmental syndrome, that is characterized by developmental delay, cognitive impairment, hypotonia, autistic features, behavior abnormalities and dysmorphic facial features. JARID2 encodes a transcriptional repressor protein that regulates the activity of various histone methyltransferase complexes. However, the molecular etiology is not fully understood, and JARID2-neurodevelopmental syndrome may vary in its typical clinical phenotype. In addition, the detection of variants of uncertain significance (VUSs) often results in a delay of final diagnosis which could hamper the appropriate care. In this study we aim to detect a specific and sensitive DNA methylation signature for JARID2-neurodevelopmental syndrome. Peripheral blood DNA methylation profiles from 56 control subjects, 8 patients with (likely) pathogenic JARID2 variants and 3 patients with JARID2 VUSs were analyzed. DNA methylation analysis indicated a clear and robust separation between patients with (likely) pathogenic variants and controls. A binary model capable of classifying patients with the JARID2-neurodevelopmental syndrome was constructed on the basis of the identified episignature. Patients carrying VUSs clustered with the control group. We identified a distinct DNA methylation signature associated with JARID2-neurodevelopmental syndrome, establishing its utility as a biomarker for this syndrome and expanding the EpiSign diagnostic test.
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